是否可以在C#的HttpClient中设置自定义DNS解析器 [英] Is it possible to set custom DNS resolver in C#'s HttpClient

问题描述

我到底想要什么:

public static CustomDnsResolver : Dns 
{
   .....
}

public static void Main(string[] args) 
{
    var httpClient = new HttpClient();
    httpClient.Dns(new CustomDnsResolver());
}

基本上，我只想在HttpClient中使用我的自定义DNS解析器，而不是系统默认值，有什么方法可以实现它?

basically I just want to use my custom DNS resolver in HttpClient instead of System default, Is there any way to achieve it?

推荐答案

您拥有的用例正是Microsoft构建HttpClient堆栈的原因.它允许您借助 HttpMessageHandler 类将业务逻辑放入分层类中.您可以在 ms中找到一些示例docs 或 visualstudio杂志

The use case you have is exactly why Microsoft build the HttpClient stack. It allow you to put your business logic in layered class with the help of HttpMessageHandler class. You can find some sample in ms docs or visualstudiomagazine

void Main()
{
    var dnsHandler = new DnsHandler(new CustomDnsResolver());
    var client = new HttpClient(dnsHandler);
    var html = client.GetStringAsync("http://google.com").Result;
}

public class DnsHandler : HttpClientHandler
{
    private readonly CustomDnsResolver _dnsResolver;

    public DnsHandler(CustomDnsResolver dnsResolver)
    {
        _dnsResolver = dnsResolver;
    }

    protected override Task<HttpResponseMessage> SendAsync(HttpRequestMessage request, CancellationToken cancellationToken)
    {
        var host = request.RequestUri.Host;
        var ip = _dnsResolver.Resolve(host);

        var builder = new UriBuilder(request.RequestUri);
        builder.Host = ip;

        request.RequestUri = builder.Uri;

        return base.SendAsync(request, cancellationToken);
    }
}

public class CustomDnsResolver
{
    public string Resolve(string host)
    {
        return "127.0.0.1";
    }
}

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